1. Field of the Invention
The present invention relates to an automatic starting and stopping apparatus for an engine, which automatically stops an engine in such a case where an automobile stops at a crossing to wait for the traffic lights to change, thereby cutting down the travel fuel consumption and, more particularly, to an automatic starting and stopping apparatus for an engine, which prolongs the life of a starter motor and other mechanical components by carrying out a minimum of proper automatic stop, and which is applicable to a wider variety of car models.
2.Description of the Related Art
FIG. 7 is a circuit diagram which shows a conventional automatic starting and stopping apparatus for an engine described, for example, in Japanese Utility Model Publication No. 63-2,588. In the drawing, a battery 1 is mounted on a vehicle to serve as a power source therefor, a key switch 2 connects a terminal 2B of the battery 1 to an ignition terminal 2A and a starter terminal 2C to supply line voltage, an engine ignition circuit 3 has an ignition coil 3L, and numeral 4 denotes a normally-open starting switch.
The circuit shown in FIG. 7 includes a self-holding relay coil 5 and a self-holding contact 6; when the coil 5 is supplied with electric currents and energized, the electrical connection between terminals 6a and 6b is changed over to the electrical connection between the terminal 6a and a terminal 6c. Further, the voltage of the ignition terminal 2A is applied to the coil 5 via the self-holding contact 6, which has been electrically connected to the terminal 6c, and a normally-close canceling switch 7, the contact 6 being self-held by the coil 5.
Numeral 8 denotes a starter, which is connected to the starter terminal 2C to start the engine. An ignition electric current supply control circuit 9 is supplied with electric power by the self-holding of the contact 6 and it controls the supply of electric power to the ignition circuit 3 via a relay 9L. A starter electric current supply control circuit 10 controls the supply of electric power to the starter 8 via a relay 10L, which is energized when supplied with electric currents via the self-held contact 6.
A lighting switch 11 is closed in response to the lighting of the headlights; it applies the positive potential applied to a terminal 11a to the ignition electric current supply control circuit 9. A reverse switch 12 is closed when the vehicle moves back; it applies the positive potential applied to a terminal 12a to the ignition electric current supply control circuit 9. A water temperature sensor 13 is represented by a normally-close switch; it is released at such a high temperature that causes the temperature of the engine cooling water to overheat, thereby cutting off the grounded state of the power input of the ignition electric current supply control circuit 9. A turn signal switch 14 is closed when the vehicle turns right; it applies the positive potential applied to a terminal 14a to the ignition electric current supply control circuit 9.
A car speed sensor 15 generates a travel signal corresponding to the car speed; it intermittently issues the travel signal through a permanent magnet (not shown), which is fixed on an axle and rotates while the vehicle is traveling. An accelerator switch 16 closes when an accelerator pedal is depressed and it places the power input of the starter electric current supply control circuit 10 in the grounded state. A slope switch 18 closes when it detects the inclination of a slope; it places the power input of the ignition electric current supply control circuit 9 in the grounded state when the vehicle starts climbing the slope.
A clutch switch 19 closes to place the power input of the starter electric current supply control circuit 10 in the grounded state and issues a disengagement detection signal when a clutch pedal is fully depressed to completely disengage the clutch. An engine start detection circuit 20 detects the voltage of an alternator 20a generated due to the revolution of the engine, whereby to indirectly detect the start of the engine, and it places the starter electric current supply control circuit 10 in a shutoff state to cut off the supply of electric power to the starter 8.
A normally-close brake switch 23 is released when a brake pedal is depressed. Neutral switches 24, 25 are interlocked with a shift lever 26 of a transmission; they are released when the shift lever 26 is set in the neutral position.
Diodes 9D.sub.1 through 9D.sub.6, resistors 9R.sub.1 through 9R.sub.6, capacitors 9C.sub.1 and 9C.sub.2, and transistors 9Tr.sub.1 through 9Tr.sub.4 constitute the ignition electric current supply control circuit 9. A diode 10D, a resistor 10R, and transistors 10Tr.sub.1 and 10Tr.sub.2 constitute the starter electric current supply control circuit 10. Transistors 20Tr.sub.1 and 20Tr.sub.2 constitute the engine start detection circuit 20.
FIG. 8 is an explanatory drawing which shows the operation of a manually-operated automotive clutch, 21 being a driver's foot, 22 being a clutch pedal, and 22a and 22b indicating the positions of the clutch pedal 22. The clutch switch 19 is arranged so that it closes when the clutch pedal 22 is fully depressed to the position 22b.
The operation of the conventional automatic starting and stopping apparatus for an engine will now be described with reference to FIG. 7. First, turning the key switch 2 ON to close the starting switch 4 causes the electric power of the battery 1 to be applied to the coil 5 via the key switch 2 and the starting switch 4. The coil 5, which has been supplied with electric currents, electrically connects the terminals 6a and 6c of the contact 6. As a result, even when the starting switch 4 is released, the contact 6 is self-held because exciting currents flow through the coil 5 via the contact 6 and the canceling switch 7. Hence, the line voltage from the battery 1 is applied to the ignition electric current supply control circuit 9, the starter electric current supply control circuit 10, and the engine start detection circuit 20 via the contact 6.
When the engine is started and the vehicle starts travelling, the car speed sensor 15 turns ON and OFF. This ON/OFF operation causes the electric charges to be charged in the capacitor 9C.sub.1 through the resistor 9R.sub.3 then they are charged in the capacitor 9C.sub.2 through the diode 9D.sub.3, thus generating positive voltage. This positive voltage turns the transistor 9Tr.sub.2 ON and the potential of the collector thereof becomes the ground potential, which is applied to the base of the subsequent transistor 9Tr.sub.3 , turning the transistor 9Tr.sub.3 OFF, with the positive-potential applied to the base of the subsequent output transistor 9Tr.sub.4, thus turning it ON.
When the output transistor 9Tr.sub.4 is turned ON, the coil of the ignition electric current supply relay 9L connected to the collector is supplied with electric power and the contact of the ignition electric current supply relay 9L closes. Through this closed contact, the currents are supplied from the battery 1 to an ignition coil 3L of the ignition circuit 3, and the engine continues to run.
After that, when the vehicle stops, the car speed sensor 15 stops issuing the travel signal. At this time, the driver is depressing the brake pedal and the brake switch 23 is released. Further, when the neutral switches 24 and 25 are released, and the accelerator switch 16 and the slope switch 18 are open, with the shift lever 26 of the transmission set in the neutral position, the positive potential is continuously applied to the base of the transistor 9Tr.sub.1 via the resistor 9R.sub.2, causing the transistor to turn ON and the collector of the transistor 9Tr.sub.1 to provide the ground potential, thereby preventing the capacitor 9C.sub.2 from being charged.
Moreover, when the turn signal switch 14 is open, the charging of tile capacitor 9C.sub.2 with the positive potential applied to the terminal 14a is not carried out; therefore, the potential of the capacitor 9C.sub.2 becomes 0 V. This turns the transistor 9Tr.sub.2 OFF and turns the transistor 9Tr.sub.3 ON. With the transistor 9Tr.sub.3 turned ON, if the lighting switch 11 and the reverse switch 12 are open and the water temperature sensor 13 is closed, then the output transistor 9Tr.sub.4 turns OFF, causing the contact of the ignition electric current supply relay 9L to be released and the electric power supplied to the engine ignition circuit 3 to be cut off, thus stopping the engine.
On the other hand, at the time of automatic start, fully depressing the clutch pedal 22 to the position 22b (FIG. 8) and setting the shift lever 26 of the transmission in a position other than the neutral cause the clutch switch 19 and the neutral switches 24 and 25 to be closed. When the neutral switch 25 is closed, the transistor 9Tr.sub.1 turns OFF because the potential of the base thereof becomes the ground potential.
Thus, the charging currents flow into the capacitor 9C.sub.2 via the resistor 9R.sub.3 and the diodes 9D.sub.4 and 9D.sub.6 to provide a predetermined charging voltage; therefore, the transistor 9Tr.sub.2 turns ON, the transistor 9Tr.sub.3 turns OFF, and the transistor 9Tr.sub.4 turns ON, causing the currents to flow into the coil of the ignition electric current supply relay 9L. In addition, the contact of the ignition electric current supply relay 9L closes, thus supplying electric currents to the ignition coil 3L of the ignition circuit 3.
Further, when the neutral switch 24 and the clutch switch 19 are closed, the anode of the diode 10D is grounded, thus bypassing the base currents, which flow through the transistor 10Tr.sub.1 via the diode 10D, to the earth via the resistor 10R, the clutch switch 19, and the neutral switch 24.
Accordingly, the voltage reduced through the resistor 10R is applied to the base of the transistor 20Tr.sub.2 of the engine start detection circuit 20, turning the transistor ON; when the transistor 10Tr.sub.1 turns OFF and the output transistor 10Tr.sub.2 turns ON, the starter electric current supply relay 10L is closed to energize the starter 8, thereby automatically starting the engine. After the engine is automatically started, the engine start detection circuit 20 applies the output of the alternator 20a to the base of the transistor 20Tr.sub.1 through the filter to turn the transmission ON and turn the following transistor 20Tr.sub.2 OFF.
As a result, the potential of the collector of the transistor 20Tr.sub.2 turns to a positive potential which is applied to the base of the transistor 10Tr.sub.1 of the starter electric current supply control circuit 10 to turn the transistor 10Tr.sub.1 ON and turn the output transistor 10Tr.sub.2 OFF, thereby stopping the supply of power to the starter 8.
The operations described above can be summarized as shown in Table 1 below:
TABLE 1 ______________________________________ [Engine] [T/M] [Clutch] [Brake] [Car Speed] ______________________________________ Stop N -- SW23 OFF 0 (Stop) Start Other than N SW19 ON -- 0 (Stop) ______________________________________
where T/M denotes the transmission and N stands for neutral in Table 1. The car speed is detected by the car speed sensor 15 and it is zero in both automatic stop and automatic start. In addition, as previously described, more conditions, wherein the slope switch 18, the turn signal switch 14, the accelerator switch 16, the lighting switch 11, and the reverse switch 12 are open, and the water temperature sensor 13 is closed, are added in the case of the automatic stop. The opposite from these conditions provides the conditions for maintaining the operation.
Thus, the automatic stop of the engine is performed on condition that the brake pedal is depressed at the zero car speed and also the transmission is in the neutral position; therefore, the engine can be stopped even if the brake is engaged to stop the vehicle with the shift lever 26 of the transmission shifted to the neutral position, and the clutch pedal 22 not being depressed, at the time of stopping the vehicle.
Likewise, at the time of starting the vehicle, the automatic start is performed when the clutch switch 19 is fully depressed and also the shift lever 26 of the transmission is set in a position other than the neutral. This enables the confirmation of the driver's intention by the shift position of the transmission and it also prevents the starter 8 from being started and energized with the clutch engaged incompletely, thus leading to higher reliability.
The conventional automatic starting and stopping apparatus for an engine presented a problem of a shortened lives of mechanical components, including the starter motor 8 for starting the engine, because vehicles must stop at pedestrian crossings, railroad crossings or before merging into main streets from side streets in urban districts or the like in addition to stopping due to traffic jams, wherein the distances between vehicles become shorter, or due to waiting for the traffic lights to change; thus the engine is stopped frequently, making the stop and start of the engine complicated as a whole.
The use of the clutch pedal 22 as the switch for stopping the engine presented another problem in that the conventional apparatus could not be applied to automatic vehicles, restricting the applicable car models.